Adhesive-repellent coatings having a controllable degree of adhesive-repellency have been described in U.S. Pat. No. 4,154,714 to Hockemeyer et al. These adhesive-repellent coatings are prepared by applying to the surfaces to be rendered adhesive-repellent a composition containing organopolysiloxanes having SiC-bonded groups which contain an aliphatic multiple bond, organopolysiloxanes having Si-bonded hydrogen and a catalyst which promotes the addition of Si-bonded hydrogen to an aliphatic multiple bond and thereafter crosslinking the organopolysiloxanes.
U.S. Pat. No. 4,260,726 to Deubzer et al describes thermosetting compositions containing organopolysiloxanes having Si-bonded hydrogen and aliphatic multiple bonds which can be crosslinked by the addition of the Si-bonded hydrogen to an aliphatic multiple bond in the presence of catalysts, such as platinum, and an additive which retards or prevents crosslinking at least at room temperature and consists at least partially of at least one organic compound having at least one group of the formula ##STR2##
The patent further provides that the aliphatic multiple bond and Si-bonded hydrogen may be present in the same organo-silicon compound, in which the Si-bonded hydrogen is present in an amount of from 0.1 to 15 Si-bonded hydrogen atoms for each aliphatic multiple bond. These thermosetting organopolysiloxane compositions may be used in preparing coatings which repel adhesive substances. However, it should be emphasized that the compositions disclosed in U.S. Pat. No. 4,260,726 do not contain any provisions for regulating the degree of adhesive-repellency.
U.S. Pat. No. 4,043,977 to deMontigny et al describes a composition for preparing adhesive-repellent coatings which contain organopolysiloxanes having SiC-bonded vinyl groups, i.e., groups having an aliphatic multiple bond, and Si-bonded hydrogen in one and the same molecule, in which the organopolysiloxane contains up to 10 silicon atoms per molecule and a platinum complex. In contrast to the teachings of U.S. Pat. No. 4,043,977, the organopolysiloxanes having SiC-bonded groups which contain an aliphatic multiple bond and Si-bonded hydrogen in one and the same molecule used in the present invention, contain more than 10 silicon atoms per molecule. Moreover, this reference does not disclose a coating composition in which the degree of adhesive repellency is controlled.
Even though the adhesive properties of adhesives decrease when they are in contact with the coatings prepared in accordance with this invention over a prolonged period of time, the decrease is less than in comparable coatings known heretofore.
Therefore, it is an object of the present invention to provide coating compositions which will impart release properties to substrates coated therewith. Another object of this invention is to provide coating compositions which will impart non-adherent properties to substrates coated therewith when contacted with adhesive materials. Another object of this invention is to provide compositions which cure rapidly when applied to substrates. A further object of this invention is to provide coatings which have a predetermined degree of repellency when contacted with adhesive materials. A still further object of this invention is to provide a process for preparing adhesive-repellent coatings having a predetermined degree of repellency.